Optical transmitters are devices that send optical signals over optical signal transmission media in optical and optoelectronic networks. Typically, an optical transmitter is included with optical receiver in an optical transceiver. Recently, multi-channel optical transceivers have been made to communicate multiple signals over a single transmission medium.
Multiple wavelength division multiplexing (WDM) has been used for optical interfaces for data rates at 40 Gbps (e.g., 40 GBASE LR4 and ER4) and 100 Gbps (e.g., 100 GBASE LR4 and ER4). The IEEE 802.3ba-2010 standard defines four WDM channels multiplexed onto a single fiber for these interfaces. The 40 GBASE-LR4/ER4 interface defines CWDM grids with center wavelengths of 1271, 1291, 1311, and 1331 nm. The 100 GBASE-LR4/ER4 interface defines LAN-WDM channels with center wavelengths of 1295.56, 1300.05, 1304.58, and 1309.14 nm.
For various reasons, it is important, if not critical, to fabricate compact, low cost optical subassemblies (OSAs) for use in such transceivers. Thus, there is demand for ever-smaller optical devices, particularly in multi-channel optical transmitters and transceivers.
This “Discussion of the Background” section is provided for background information only. The statements in this “Discussion of the Background” are not an admission that the subject matter disclosed in this “Discussion of the Background” section constitutes prior art to the present disclosure, and no part of this “Discussion of the Background” section may be used as an admission that any part of this application, including this “Discussion of the Background” section, constitutes prior art to the present disclosure.